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<p>This study investigated the application of NH<sub>3</sub>–CO mixed gas as a sustainable reducing agent in ironmaking processes. A combined experimental approach was employed, utilizing a horizontal furnace for single-pellet experiments, a low-temperature reduction testing system for 500&#xa0;g pellet batches, and thermogravimetric analysis (TGA) for kinetic studies. The results demonstrate a remarkable synergistic effect in the mixed gas system. At lower temperatures, generated H<sub>2</sub> from NH<sub>3</sub> decomposition played a crucial role, while NH<sub>3</sub> itself became the dominant reductant at elevated temperatures, achieving complete iron oxide reduction. Microstructural characterization revealed that higher NH<sub>3</sub> proportions facilitated the development of interconnected pore channels and promoted the formation of a continuous metallic iron skeleton. Kinetic analysis identified a two-stage mechanism, transitioning from initial chemical reaction control to subsequent product-layer diffusion control. The apparent activation energy for the mixed gases ranged from 23.92 to 60.51&#xa0;kJ&#xa0;mol<sup>−1</sup>, significantly lower than values reported for pure NH<sub>3</sub> or CO systems, confirming the kinetic advantages of the synergistic approach. This work not only validates the technical feasibility of NH<sub>3</sub>–CO mixtures but also provides fundamental insights and practical parameters for developing next-generation low-carbon ironmaking technologies.</p>

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Experimental Investigation on Reduction Behavior and Kinetics of Iron Ore Pellets by NH3/CO Mixture: Effects of Ratio and Temperature

  • 期刊论文

  • 发表日期：

    2025年12月10日

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  • Li Li,
  • Xianchun Li,
  • Yanjiang Li,
  • Shaoyan Wang

摘要

This study investigated the application of NH3–CO mixed gas as a sustainable reducing agent in ironmaking processes. A combined experimental approach was employed, utilizing a horizontal furnace for single-pellet experiments, a low-temperature reduction testing system for 500 g pellet batches, and thermogravimetric analysis (TGA) for kinetic studies. The results demonstrate a remarkable synergistic effect in the mixed gas system. At lower temperatures, generated H2 from NH3 decomposition played a crucial role, while NH3 itself became the dominant reductant at elevated temperatures, achieving complete iron oxide reduction. Microstructural characterization revealed that higher NH3 proportions facilitated the development of interconnected pore channels and promoted the formation of a continuous metallic iron skeleton. Kinetic analysis identified a two-stage mechanism, transitioning from initial chemical reaction control to subsequent product-layer diffusion control. The apparent activation energy for the mixed gases ranged from 23.92 to 60.51 kJ mol−1, significantly lower than values reported for pure NH3 or CO systems, confirming the kinetic advantages of the synergistic approach. This work not only validates the technical feasibility of NH3–CO mixtures but also provides fundamental insights and practical parameters for developing next-generation low-carbon ironmaking technologies.